This Article Full Text Full Text (PDF) Supplemental Materials Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Teng, C.-L. Articles by Bryant, R. G. Search for Related Content PubMed PubMed Citation Articles by Teng, C.-L. Articles by Bryant, R. G.

Mapping Oxygen Accessibility to Ribonuclease A Using High-Resolution NMR Relaxation Spectroscopy

Ching-Ling Teng ^* and Robert G. Bryant ^* 

^* Biophysics Program and Chemistry Department, University of Virginia, Charlottesville, Virginia 22904-4319

Correspondence: Address reprint requests to Robert G. Bryant, Chemistry Department, University of Virginia, McCormick Rd., PO Box 400319, Charlottesville, VA 22904-4319. Tel.: 434-924-1494; 434-924-3567; E-mail: rgb4g{at}virginia.edu.

Paramagnetic contributions to nuclear magnetic spin-lattice relaxation rate constant induced by freely diffusing molecular oxygen measured at hundreds of different protein proton sites provide a direct means for characterizing the exploration of the protein by oxygen. This report focuses on regions of ribonuclease A where the rate constant enhancements are either quite large or quite small. We find that there are several regions of enhanced oxygen affinity for the protein both on the surface and in interior pockets where sufficient free volume permits. Oxygen has weak associative interactions with a number of surface crevices that are generally between secondary structural elements of the protein fold. Several regions near the surface have higher than expected accessibility to oxygen indicating that structural fluctuations in the protein provide intermolecular access. Oxygen penetrates part of the hydrophobic interior, but affinity does not correlate simply with hydrophobicity indices. Oxygen is excluded from regions of high interior packing density and a few surface sites where x-ray diffraction data have indicated the presence of specific hydration with high occupancy.

This article has been cited by other articles:

				V. Venditti, N. Niccolai, and S. E. Butcher Measuring the dynamic surface accessibility of RNA with the small paramagnetic molecule TEMPOL Nucleic Acids Res., March 27, 2008; 36(4): e20 - e20. [Abstract] [Full Text] [PDF]